Desalination of brackish water is already commonplace in the U.S., where it is used to meet treaty obligations for river water entering Mexico.

Desalination of ocean water is common in the Middle East, where a number of countries use oil-fired stills to provide city drinking water.

The price of desalination is rapidly declining. A modern, large, efficient plant is within 20% of the cost of developing a new, local source of fresh water.
Desalination stills now control pressure, temperature and brine concentrations to optimize the water extraction expense.
Other methods of desalination include reverse osmosis and pressure barrier osmosis[?].
Nuclear-powered desalination could be very economical on a large scale.